As the largest producer of autopilots in the world, we get a lot of calls from aircraft owners looking for troubleshooting help. And although your autopilot is one of the most sophisticated parts of your airplane the fixes are often surprisingly simple.
Disclaimer here: This is NOT a DIY project. You need to have a qualified and licensed avionics technician inspect and troubleshoot any autopilot anomaly. Autopilots are integrated with a number of your aircraft’s systems and problems with any of them can first show up as an “autopilot” issue.
But, until you can get your airplane to your nearest avionics shop there are a few things to look at.
Basic Autopilot Troubleshooting
First off, read the POH. You’d be shocked at how many times an owner will take their airplane into an avionics shop reporting a problem with their autopilot only to lean that they were doing it wrong.
For example, one pilot reported that whenever he put his A/P on vertical speed mode the airplane would pitch up to a near stall. The simple fix was he was selecting a vertical speed that was too high for his airplane. The unit was doing exactly what it was designed to do.
Secondly, take time to inspect your airplane. Another owner went into his avionic shop complaining that is A/P was “pitch/porpoising” during cruise. The technician started to look at the airplane and found that the owner had two cases of oil and a case of bottled water amongst other stuff in the rear cargo area. That out-of-C.G. situation had the autopilot’s transducer hunting throughout the flight.
If you do suspect a problem with your autopilot (or associated components), go fly it in good weather and try all the various modes. If it’s not holding heading try it in the NAV mode. If that works, then you may have a DG problem not an autopilot problem.
Keeping that thought, make sure you take notes when you suspect an autopilot or for that matter an issue with any system on your airplane. Write down all the details of the aircraft’s configuration, weather, load, etc., when you noticed the problem.
Your avionics shop’s technician needs information – tangible, viable, repeatable information. What should this information contain? Any and every bit of insight as to what was going on when the autopilot anomaly occurred. And make the notations as concise as possible. When it comes to autopilot troubleshooting: every detail matters.
And finally, take time to review what to do in the worst-case scenario. Make sure you know which circuit breaker or fuse to pull should you need to take the A/P offline. Any emergency is no time to be flipping through the POH.
Until next time, fly safely,